kernel/linux.git, branch v4.4.254

Linux 4.4.254

2021-01-30T12:25:58+00:00

Tested-by: Pavel Machek (CIP) Tested-by: Linux Kernel Functional Testing Link: https://lore.kernel.org/r/20210129105909.630107942@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

x86/boot/compressed: Disable relocation relaxation

2021-01-30T12:25:58+00:00

commit 09e43968db40c33a73e9ddbfd937f46d5c334924 upstream. The x86-64 psABI [0] specifies special relocation types (R_X86_64_[REX_]GOTPCRELX) for indirection through the Global Offset Table, semantically equivalent to R_X86_64_GOTPCREL, which the linker can take advantage of for optimization (relaxation) at link time. This is supported by LLD and binutils versions 2.26 onwards. The compressed kernel is position-independent code, however, when using LLD or binutils versions before 2.27, it must be linked without the -pie option. In this case, the linker may optimize certain instructions into a non-position-independent form, by converting foo@GOTPCREL(%rip) to $foo. This potential issue has been present with LLD and binutils-2.26 for a long time, but it has never manifested itself before now: - LLD and binutils-2.26 only relax movq foo@GOTPCREL(%rip), %reg to leaq foo(%rip), %reg which is still position-independent, rather than mov $foo, %reg which is permitted by the psABI when -pie is not enabled. - GCC happens to only generate GOTPCREL relocations on mov instructions. - CLang does generate GOTPCREL relocations on non-mov instructions, but when building the compressed kernel, it uses its integrated assembler (due to the redefinition of KBUILD_CFLAGS dropping -no-integrated-as), which has so far defaulted to not generating the GOTPCRELX relocations. Nick Desaulniers reports [1,2]: "A recent change [3] to a default value of configuration variable (ENABLE_X86_RELAX_RELOCATIONS OFF -> ON) in LLVM now causes Clang's integrated assembler to emit R_X86_64_GOTPCRELX/R_X86_64_REX_GOTPCRELX relocations. LLD will relax instructions with these relocations based on whether the image is being linked as position independent or not. When not, then LLD will relax these instructions to use absolute addressing mode (R_RELAX_GOT_PC_NOPIC). This causes kernels built with Clang and linked with LLD to fail to boot." Patch series [4] is a solution to allow the compressed kernel to be linked with -pie unconditionally, but even if merged is unlikely to be backported. As a simple solution that can be applied to stable as well, prevent the assembler from generating the relaxed relocation types using the -mrelax-relocations=no option. For ease of backporting, do this unconditionally. [0] https://gitlab.com/x86-psABIs/x86-64-ABI/-/blob/master/x86-64-ABI/linker-optimization.tex#L65 [1] https://lore.kernel.org/lkml/20200807194100.3570838-1-ndesaulniers@google.com/ [2] https://github.com/ClangBuiltLinux/linux/issues/1121 [3] https://reviews.llvm.org/rGc41a18cf61790fc898dcda1055c3efbf442c14c0 [4] https://lore.kernel.org/lkml/20200731202738.2577854-1-nivedita@alum.mit.edu/ Reported-by: Nick Desaulniers Signed-off-by: Arvind Sankar Signed-off-by: Ingo Molnar Tested-by: Nick Desaulniers Tested-by: Sedat Dilek Acked-by: Ard Biesheuvel Reviewed-by: Nick Desaulniers Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200812004308.1448603-1-nivedita@alum.mit.edu [nc: Backport to 4.4] Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman

xen-blkback: set ring->xenblkd to NULL after kthread_stop()

2021-01-30T12:25:57+00:00

commit 1c728719a4da6e654afb9cc047164755072ed7c9 upstream. When xen_blkif_disconnect() is called, the kernel thread behind the block interface is stopped by calling kthread_stop(ring->xenblkd). The ring->xenblkd thread pointer being non-NULL determines if the thread has been already stopped. Normally, the thread's function xen_blkif_schedule() sets the ring->xenblkd to NULL, when the thread's main loop ends. However, when the thread has not been started yet (i.e. wake_up_process() has not been called on it), the xen_blkif_schedule() function would not be called yet. In such case the kthread_stop() call returns -EINTR and the ring->xenblkd remains dangling. When this happens, any consecutive call to xen_blkif_disconnect (for example in frontend_changed() callback) leads to a kernel crash in kthread_stop() (e.g. NULL pointer dereference in exit_creds()). This is XSA-350. Cc: # 4.12 Fixes: a24fa22ce22a ("xen/blkback: don't use xen_blkif_get() in xen-blkback kthread") Reported-by: Olivier Benjamin Reported-by: Pawel Wieczorkiewicz Signed-off-by: Pawel Wieczorkiewicz Reviewed-by: Julien Grall Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross [iwamatsu: change from ring to blkif] Signed-off-by: Nobuhiro Iwamatsu Signed-off-by: Greg Kroah-Hartman

tracing: Fix race in trace_open and buffer resize call

2021-01-30T12:25:57+00:00

commit bbeb97464eefc65f506084fd9f18f21653e01137 upstream. Below race can come, if trace_open and resize of cpu buffer is running parallely on different cpus CPUX CPUY ring_buffer_resize atomic_read(&buffer->resize_disabled) tracing_open tracing_reset_online_cpus ring_buffer_reset_cpu rb_reset_cpu rb_update_pages remove/insert pages resetting pointer This race can cause data abort or some times infinte loop in rb_remove_pages and rb_insert_pages while checking pages for sanity. Take buffer lock to fix this. Link: https://lkml.kernel.org/r/1601976833-24377-1-git-send-email-gkohli@codeaurora.org Cc: stable@vger.kernel.org Fixes: 83f40318dab00 ("ring-buffer: Make removal of ring buffer pages atomic") Reported-by: Denis Efremov Signed-off-by: Gaurav Kohli Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

Revert "mm/slub: fix a memory leak in sysfs_slab_add()"

2021-01-30T12:25:57+00:00

commit 757fed1d0898b893d7daa84183947c70f27632f3 upstream. This reverts commit dde3c6b72a16c2db826f54b2d49bdea26c3534a2. syzbot report a double-free bug. The following case can cause this bug. - mm/slab_common.c: create_cache(): if the __kmem_cache_create() fails, it does: out_free_cache: kmem_cache_free(kmem_cache, s); - but __kmem_cache_create() - at least for slub() - will have done sysfs_slab_add(s) -> sysfs_create_group() .. fails .. -> kobject_del(&s->kobj); .. which frees s ... We can't remove the kmem_cache_free() in create_cache(), because other error cases of __kmem_cache_create() do not free this. So, revert the commit dde3c6b72a16 ("mm/slub: fix a memory leak in sysfs_slab_add()") to fix this. Reported-by: syzbot+d0bd96b4696c1ef67991@syzkaller.appspotmail.com Fixes: dde3c6b72a16 ("mm/slub: fix a memory leak in sysfs_slab_add()") Acked-by: Vlastimil Babka Signed-off-by: Wang Hai Cc: Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

net_sched: avoid shift-out-of-bounds in tcindex_set_parms()

2021-01-30T12:25:57+00:00

commit bcd0cf19ef8258ac31b9a20248b05c15a1f4b4b0 upstream. tc_index being 16bit wide, we need to check that TCA_TCINDEX_SHIFT attribute is not silly. UBSAN: shift-out-of-bounds in net/sched/cls_tcindex.c:260:29 shift exponent 255 is too large for 32-bit type 'int' CPU: 0 PID: 8516 Comm: syz-executor228 Not tainted 5.10.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395 valid_perfect_hash net/sched/cls_tcindex.c:260 [inline] tcindex_set_parms.cold+0x1b/0x215 net/sched/cls_tcindex.c:425 tcindex_change+0x232/0x340 net/sched/cls_tcindex.c:546 tc_new_tfilter+0x13fb/0x21b0 net/sched/cls_api.c:2127 rtnetlink_rcv_msg+0x8b6/0xb80 net/core/rtnetlink.c:5555 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330 netlink_sendmsg+0x907/0xe40 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2336 ___sys_sendmsg+0xf3/0x170 net/socket.c:2390 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2423 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Reported-by: syzbot Link: https://lore.kernel.org/r/20210114185229.1742255-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

ipv6: create multicast route with RTPROT_KERNEL

2021-01-30T12:25:57+00:00

commit a826b04303a40d52439aa141035fca5654ccaccd upstream. The ff00::/8 multicast route is created without specifying the fc_protocol field, so the default RTPROT_BOOT value is used: $ ip -6 -d route unicast ::1 dev lo proto kernel scope global metric 256 pref medium unicast fe80::/64 dev eth0 proto kernel scope global metric 256 pref medium unicast ff00::/8 dev eth0 proto boot scope global metric 256 pref medium As the documentation says, this value identifies routes installed during boot, but the route is created when interface is set up. Change the value to RTPROT_KERNEL which is a better value. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Matteo Croce Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

skbuff: back tiny skbs with kmalloc() in __netdev_alloc_skb() too

2021-01-30T12:25:57+00:00

commit 66c556025d687dbdd0f748c5e1df89c977b6c02a upstream. Commit 3226b158e67c ("net: avoid 32 x truesize under-estimation for tiny skbs") ensured that skbs with data size lower than 1025 bytes will be kmalloc'ed to avoid excessive page cache fragmentation and memory consumption. However, the fix adressed only __napi_alloc_skb() (primarily for virtio_net and napi_get_frags()), but the issue can still be achieved through __netdev_alloc_skb(), which is still used by several drivers. Drivers often allocate a tiny skb for headers and place the rest of the frame to frags (so-called copybreak). Mirror the condition to __netdev_alloc_skb() to handle this case too. Since v1 [0]: - fix "Fixes:" tag; - refine commit message (mention copybreak usecase). [0] https://lore.kernel.org/netdev/20210114235423.232737-1-alobakin@pm.me Fixes: a1c7fff7e18f ("net: netdev_alloc_skb() use build_skb()") Signed-off-by: Alexander Lobakin Link: https://lore.kernel.org/r/20210115150354.85967-1-alobakin@pm.me Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sh_eth: Fix power down vs. is_opened flag ordering

2021-01-30T12:25:56+00:00

commit f6a2e94b3f9d89cb40771ff746b16b5687650cbb upstream. sh_eth_close() does a synchronous power down of the device before marking it closed. Revert the order, to make sure the device is never marked opened while suspended. While at it, use pm_runtime_put() instead of pm_runtime_put_sync(), as there is no reason to do a synchronous power down. Fixes: 7fa2955ff70ce453 ("sh_eth: Fix sleeping function called from invalid context") Signed-off-by: Geert Uytterhoeven Reviewed-by: Sergei Shtylyov Reviewed-by: Niklas Söderlund Link: https://lore.kernel.org/r/20210118150812.796791-1-geert+renesas@glider.be Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

sh: dma: fix kconfig dependency for G2_DMA

2021-01-30T12:25:56+00:00

commit f477a538c14d07f8c45e554c8c5208d588514e98 upstream. When G2_DMA is enabled and SH_DMA is disabled, it results in the following Kbuild warning: WARNING: unmet direct dependencies detected for SH_DMA_API Depends on [n]: SH_DMA [=n] Selected by [y]: - G2_DMA [=y] && SH_DREAMCAST [=y] The reason is that G2_DMA selects SH_DMA_API without depending on or selecting SH_DMA while SH_DMA_API depends on SH_DMA. When G2_DMA was first introduced with commit 40f49e7ed77f ("sh: dma: Make G2 DMA configurable."), this wasn't an issue since SH_DMA_API didn't have such dependency, and this way was the only way to enable it since SH_DMA_API was non-visible. However, later SH_DMA_API was made visible and dependent on SH_DMA with commit d8902adcc1a9 ("dmaengine: sh: Add Support SuperH DMA Engine driver"). Let G2_DMA depend on SH_DMA_API instead to avoid Kbuild issues. Fixes: d8902adcc1a9 ("dmaengine: sh: Add Support SuperH DMA Engine driver") Signed-off-by: Necip Fazil Yildiran Signed-off-by: Rich Felker Signed-off-by: Greg Kroah-Hartman